Qiang Xue
10 years ago
4 changed files with 180 additions and 56 deletions
@ -1,96 +1,217 @@
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Error Handling |
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============== |
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Handling Errors |
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=============== |
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> Note: This section is under development. |
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Yii includes a built-in [[yii\web\ErrorHandler|error handler]] which makes error handling a much more pleasant |
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experience than before. In particular, the Yii error handler does the followings to improve error handling: |
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Error handling in Yii is different than handling errors in plain PHP. First of all, Yii will convert all non-fatal errors |
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to *exceptions*: |
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* All non-fatal PHP errors (e.g. warnings, notices) are converted into catchable exceptions. |
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* Exceptions and fatal PHP errors are displayed with detailed call stack information and source code lines |
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in debug mode. |
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* Support using a dedicated [controller action](structure-actions.md) to display errors. |
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* Support different error response formats. |
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|
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The [[yii\web\ErrorHandler|error handler]] is enabled by default. You may disable it by defining the constant |
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`YII_ENABLE_ERROR_HANDLER` to be false in the [entry script](structure-entry-scripts.md) of your application. |
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|
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## Using Error Handler <a name="using-error-handler"></a> |
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The [[yii\web\ErrorHandler|error handler]] is registered as an application component named `errorHandler`. |
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You may configure it in the application configuration like the following: |
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```php |
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return [ |
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'components' => [ |
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'errorHandler' => [ |
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'maxSourceLines' => 20, |
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], |
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], |
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]; |
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``` |
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With the above configuration, the number of source code lines to be displayed in exception pages will be up to 20. |
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As aforementioned, the error handler turns all non-fatal PHP errors into catchable exceptions. This means you can |
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use the following code to deal with PHP errors: |
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```php |
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use yii\base\ErrorException; |
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use Yii; |
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use yii\base\ErrorException; |
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try { |
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10/0; |
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} catch (ErrorException $e) { |
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Yii::warning("Tried dividing by zero."); |
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Yii::warning("Division by zero."); |
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} |
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// execution may continue |
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// execution continues... |
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``` |
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As demonstrated above you may handle errors using `try`-`catch`. |
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If you want to show an error page telling the user that his request is invalid or unexpected, you may simply |
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throw an [[yii\web\HttpException|HTTP exception]], such as [[yii\web\NotFoundHttpException]]. The error handler |
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will correctly set the HTTP status code of the response and use an appropriate error view to display the error |
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message. |
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Second, even fatal errors in Yii are rendered in a nice way. This means that in debugging mode, you can trace the causes |
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of fatal errors in order to more quickly identify the cause of the problem. |
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```php |
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use yii\web\NotFoundHttpException; |
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throw new NotFoundHttpException(); |
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``` |
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## Customizing Error Display <a name="customizing-error-display"></a> |
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The [[yii\web\ErrorHandler|error handler]] adjusts error display according to the value of the constant `YII_DEBUG`. |
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When `YII_DEBUG` is true (meaning in debug mode), the error handler will display exceptions with detailed call |
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stack information and source code lines to help easier debugging. And when `YII_DEBUG` is false, only the error |
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message will be displayed to prevent from revealing sensitive information of the application. |
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> Info: If an exception is a descendant of [[yii\base\UserException]], no call stack will be displayed regardless |
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the value of `YII_DEBUG`. This is because such exceptions are considered to be caused by user mistakes and the |
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developers do not need to fix anything. |
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By default, the [[yii\web\ErrorHandler|error handler]] displays errors using two [views](structure-views.md): |
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* `@yii/views/errorHandler/error.php`: used when errors should be displayed WITHOUT call stack information. |
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When `YII_DEBUG` is false, this is the only error view to be displayed. |
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* `@yii/views/errorHandler/exception.php`: used when errors should be displayed WITH call stack information. |
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Rendering errors in a dedicated controller action |
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------------------------------------------------- |
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You can configure the [[yii\web\ErrorHandler::errorView|errorView]] and [[yii\web\ErrorHandler::exceptionView|exceptionView]] |
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properties of the error handler to use your own views to customize the error display. |
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The default Yii error page is great when developing a site, and is acceptable for production sites if `YII_DEBUG` |
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is turned off in your bootstrap `index.php` file. But you may want to customize the default error page to make it |
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more suitable for your project. |
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The easiest way to create a custom error page it is to use a dedicated controller action for error rendering. First, |
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you'll need to configure the `errorHandler` component in the application's configuration: |
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### Using Error Actions <a name="using-error-actions"></a> |
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A better way of customizing the error display is to use dedicated error [actions](structure-controllers.md). |
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To do so, first configure the [[yii\web\ErrorHandler::errorAction|errorAction]] property of the `errorHandler` |
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component like the following: |
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```php |
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// ... |
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'components' => [ |
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// ... |
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'errorHandler' => [ |
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'errorAction' => 'site/error', |
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], |
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] |
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return [ |
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'components' => [ |
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'errorHandler' => [ |
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'errorAction' => 'site/error', |
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], |
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] |
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]; |
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``` |
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The [[yii\web\ErrorHandler::errorAction|errorAction]] property takes a [route](structure-controllers.md#routes) |
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to an action. The above configuration states that when an error needs to be displayed without call stack information, |
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the `site/error` action should be executed. |
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You can create the `site/error` action as follows, |
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```php |
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namespace app\controllers; |
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use Yii; |
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use yii\web\Controller; |
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class SiteController extends Controller |
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{ |
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public function actions() |
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{ |
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return [ |
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'error' => [ |
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'class' => 'yii\web\ErrorAction', |
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], |
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]; |
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} |
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} |
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``` |
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With that configuration in place, whenever an error occurs, Yii will execute the `error`-action of the `site`-controller. |
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That action should look for an exception and, if present, render the proper view file, passing along the exception: |
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The above code defines the `error` action using the [[yii\web\ErrorAction]] class which renders an error |
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using a view named `error`. |
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Besides using [[yii\web\ErrorAction]], you may also define the `error` action using an action method like the following, |
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```php |
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public function actionError() |
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{ |
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$exception = \Yii::$app->errorHandler->exception; |
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$exception = Yii::$app->errorHandler->exception; |
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if ($exception !== null) { |
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return $this->render('error', ['exception' => $exception]); |
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} |
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} |
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``` |
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Next, you would create the `views/site/error.php` file, which would make use of the exception. The exception object has |
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the following properties: |
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You should now create a view file located at `views/site/error.php`. In this view file, you can access |
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the following variables if the error action is defined as [[yii\web\ErrorAction]]: |
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- `statusCode`: the HTTP status code (e.g. 403, 500). Available for [[yii\web\HttpException|HTTP exceptions]] only. |
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- `code`: the code of the exception. |
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- `message`: the error message. |
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- `file`: the name of the PHP script file where the error occurs. |
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- `line`: the line number of the code where the error occurs. |
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- `trace`: the call stack of the error. |
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* `name`: the name of the error; |
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* `message`: the error message; |
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* `exception`: the exception object through which you can more useful information, such as HTTP status code, |
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error code, error call stack, etc. |
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> Info: If you are using the [basic application template](start-installation.md) or the [advanced application template](tutorial-advanced-app.md), |
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the error action and the error view are already defined for you. |
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Rendering errors without a dedicated controller action |
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------------------------------------------------------ |
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Instead of creating a dedicated action within the Site controller, you could just indicate to Yii what class should |
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be used to handle errors: |
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### Customizing Error Response Format <a name="error-format"></a> |
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The error handler displays errors according to the format setting of the [response](runtime-responses.md). |
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If the the [[yii\web\Response::format|response format]] is `html`, it will use the error or exception view |
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to display errors, as described in the last subsection. For other response formats, the error handler will |
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assign the array representation of the exception to the [[yii\web\Response::data]] property which will then |
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be converted to different formats accordingly. For example, if the response format is `json`, you may see |
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the following response: |
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``` |
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HTTP/1.1 404 Not Found |
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Date: Sun, 02 Mar 2014 05:31:43 GMT |
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Server: Apache/2.2.26 (Unix) DAV/2 PHP/5.4.20 mod_ssl/2.2.26 OpenSSL/0.9.8y |
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Transfer-Encoding: chunked |
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Content-Type: application/json; charset=UTF-8 |
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```php |
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public function actions() |
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{ |
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return [ |
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'error' => [ |
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'class' => 'yii\web\ErrorAction', |
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], |
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]; |
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"name": "Not Found Exception", |
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"message": "The requested resource was not found.", |
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"code": 0, |
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"status": 404 |
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} |
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``` |
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After associating the class with the error as in the above, define the `views/site/error.php` file, which will |
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automatically be used. The view will be passed three variables: |
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You may customize the error response format by responding to the `beforeSend` event of the `response` component |
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in the application configuration: |
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```php |
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return [ |
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// ... |
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'components' => [ |
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'response' => [ |
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'class' => 'yii\web\Response', |
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'on beforeSend' => function ($event) { |
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$response = $event->sender; |
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if ($response->data !== null) { |
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$response->data = [ |
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'success' => $response->isSuccessful, |
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'data' => $response->data, |
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]; |
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$response->statusCode = 200; |
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} |
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}, |
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], |
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], |
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]; |
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``` |
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- `$name`: the error name |
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- `$message`: the error message |
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- `$exception`: the exception being handled |
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The above code will reformat the error response like the following: |
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The `$exception` object will have the same properties as outlined above. |
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``` |
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HTTP/1.1 200 OK |
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Date: Sun, 02 Mar 2014 05:31:43 GMT |
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Server: Apache/2.2.26 (Unix) DAV/2 PHP/5.4.20 mod_ssl/2.2.26 OpenSSL/0.9.8y |
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Transfer-Encoding: chunked |
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Content-Type: application/json; charset=UTF-8 |
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{ |
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"success": false, |
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"data": { |
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"name": "Not Found Exception", |
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"message": "The requested resource was not found.", |
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"code": 0, |
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"status": 404 |
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} |
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} |
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``` |
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